What would be a suitable sketch of the voltage - time graph when a magnet is dropped into a coil, how would the shape change if the south pole is inserted instead
It will look something like this. Note that the second peak, which I labelled as V2, will be greater than V1 (the first peak), since it will be faster as the further it travels down (cos acceleration due to gravity), so the change in time as flux changes is shorter, meaning that the emf will be higher. This is probs the most important part that most people overlook.
If south pole entered, then the graph would just be reflected on x-axis
|V2| > |V1| , but the second peak should also be narrower since the time (t) taken for the magnet to travel between the centre of the coil to a position where the magnetic field no longer interacts with the coil is shorter because of its greater velocity (TheShy has explained this but it’s not quite evident in the sketch). The area under the two peaks are equal.